Add a config file for RTD

.readthedocs.yml

@@ -0,0 +1,39 @@
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html
+# for details
+
+---
+
+# Required
+version: 2
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+  builder: html
+  configuration: docs/rst/conf.py
+  # FIXME: enable once no warnings
+  # fail_on_warning: true
+
+# Build documentation with MkDocs
+#mkdocs:
+#  configuration: mkdocs.yml
+#  fail_on_warning: true
+
+# Optionally build your docs in additional formats
+# such as PDF and ePub
+formats: []
+
+submodules:
+  include: all  # []
+  exclude: []
+  recursive: true
+
+build:
+  image: latest
+
+# Optionally set the version of Python and requirements required
+# to build docs
+python:
+  version: 3.8
+  install: []
+  system_packages: false